Many telecommunications applications of fiber optics require the fixing (or pigtailing) of an optical fiber to the active area of a photodetector or light generating device, such as a laser, or light emitting diode. This fixing process must serve several functions, which functions include: 1) optical alignment of signals carried by the optical fibers to the optical device; 2) permanent physical attachment of the fiber to hold the alignment stable over time, temperature, shock, vibrations and other environmental conditions; and 3) electrical connection and preservation of signal integrity, which means that wire bonding, soldering, or otherwise providing electrical signal contact from the assembly to a host circuit board must be provided. Many applications also require that parasitic capacitance and/or inductance be minimized in the assembly.
The process of aligning and fixing an optical fiber to an optical device, while satisfying all of the above criteria, can be very costly. If the alignment is accomplished by a procedure referred to in the art as "active alignment" (i.e., monitoring of optoelectronically induced signals while aligning) the cost is very high because this procedure is labor intensive. A specific application in telecommunications, namely analog optical receivers used in subcarrier multiplexing applications (such as CATV receivers), has particularly demanding requirements of this fixturing process. In this application, a single single-mode optical fiber with a core diameter of approximately 8 .mu.m must be aligned to the center of a 60 .mu.m active area of a photodetector. To maintain photodetector linearity, the center or core of the optical fiber must be aligned within approximately 10 .mu.m of the center of the photodetector active area, even though the diameter of the photodetector active area is 60 .mu.m.
Prior devices in this field involve fixturing of the optical fiber in a precision machined ceramic fixture that allows for freedom of movement of the optical fiber relative to the optical device and subsequent fixing by means of an adhesive.
An example of one type of pigtailed optoelectronic assembly is disclosed in U.S. Pat. No. 5,361,317, entitled "Assembly With Fixture Aligning and Affixing an Optical Fiber to an Optical Device", issued Nov. 1, 1994 and assigned to the same assignee.
It is a purpose of the present invention to provide a new and improved single optical fiber optoelectronic transducer.
It is a further purpose of the present invention to provide a new and improved single optical fiber/device assembly which is relatively simple to fabricate and use.
It is another purpose of the present invention to provide a new and improved single optical fiber/device assembly which includes components with reduced temperature problems and with reduced capacitance.